A bottle maker believes that 11% of his bottles are defective. If the bottle maker is right, what is the probability that the proportion of defective bottles in a sample of 529529 bottles would be less than 9%9%

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Answer:

The value is   [tex]P( X < 0.09) = 0.070781[/tex]

Step-by-step explanation:

From the question we are told that

   The population proportion is  p =  0.11

   The sample size is n =  529

Generally given that the sample size is large enough (i.e n > 30), then the mean of this sampling distribution is mathematically represented as

      [tex]\mu_{x} = p = 0.11[/tex]

Generally the standard deviation of this sampling distribution is

        [tex]\sigma = \sqrt{ \frac{ p (1 - p )}{n} }[/tex]

=>     [tex]\sigma = \sqrt{ \frac{ 0.11 (1 - 0.11 )}{529} }[/tex]

=>     [tex]\sigma = 0.01360[/tex]

Generally the probability that the proportion of defective bottles in a sample of 529 bottles would be less than 9% (0.09) is mathematically represented as

     [tex]P( X < 0.09) = P(\frac{X - \mu_{x}}{\sigma} < \frac{0.09 -0.11}{ 0.01360} )[/tex]

[tex]\frac{X -\mu}{\sigma }  =  Z (The  \ standardized \  value\  of  \ X )[/tex]

     [tex]P( X < 0.09) = P(Z< -1.47 )[/tex]

Generally from the z table  the  area under the normal curve to the left corresponding to -1.47 is  

       [tex]P(Z< -1.47 ) = 0.070781[/tex]

So

       [tex]P( X < 0.09) = 0.070781[/tex]

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